(construct
 (bgp
   (triple ?:s ?:p ?:o))
 ((triple ?::?68 |http://www.w3.org/1999/02/22-rdf-syntax-ns#|:subject ?:s)
  (triple ?::?68 |http://www.w3.org/1999/02/22-rdf-syntax-ns#|:predicate ?:p)
  (triple ?::?68 |http://www.w3.org/1999/02/22-rdf-syntax-ns#|:object ?:o)))